APOE and Alzheimer disease: Alternate explanations for the differences in BPV-associated risk of dementia and cognitive decline based on sex and ApoE genotype include the possibility that the underlying pathologic mechanisms of dementia and cognitive decline in individuals with and without the ɛ4 allele differ; for example, dementia in those lacking an ɛ4 allele could be primarily vascular-related and contributed by age-related dynamic instability in BP, while individuals with the ɛ4 allele may have more Alzheimer’s disease pathology less influenced by BPV.